The present invention relates to a birds-eye-view image generation device, a birds-eye-view image generation method, and a birds-eye-view image generation program, converting captured images acquired from a plurality of imaging devices so as to be output to a display device. Particularly, the present invention relates to a birds-eye-view image combining technique for eliminating an unnatural reflection of a subject around a joint occurring when birds-eye-view images are combined and are displayed.
In recent years, there have been an increase in the number of vehicles in which cameras (imaging devices) are mounted so as for drivers to check front, rear, left and right blind spots with in-vehicle monitors, for improving the safety of road traffic. In addition, a driving supporting system which uses the cameras mounted on the vehicles has been proposed.
This driving supporting system performs a viewpoint conversion process of converting images captured by front, rear, left and right cameras of a vehicle into images (hereinafter, also referred to as a birds-eye-view images) which are viewed from the upper side of the vehicle vertically downward. In addition, the birds-eye-view images are combined so as to generate such a combined birds-eye-view image where a driver looks down at the periphery from the above of the vehicle. Thereby, the driver can continuously recognize the vehicle periphery on a single screen.
There are cases where a solid obstacle is not visible around a joint of images on a combined birds-eye-view image generated by combining a plurality of birds-eye-view images. In order to improve this, it is considered that two birds-eye-view images are displayed so as to overlap each other around the joint; however, in this case, a single solid obstacle may be seen as a double image. In addition, it is considered that two birds-eye-view images are displayed so as not to overlap each other around the joint; however, in this case, the solid obstacle may be seen to be disconnected over the joint and to be discontinuous. As above, even if the remedial measures are performed, it may be difficult for a driver to recognize an obstacle.
In relation to a reduction in visibility for a solid obstacle around the joint of birds-eye-view images, the following techniques are known. For example, a technique is known in which, when a solid obstacle is detected around a joint by obstacle detection means, a display region cutting process is performed on a single or a plurality of different definite reference heights in addition to a road surface level (first reference height), and a plurality of obtained birds-eye-view images are displayed through switching (for example, refer to Patent Reference 1). In addition, a technique is known in which it is determined whether or not there is an obstacle in a region corresponding to a joint of birds-eye-view images with sonars mounted on a vehicle, and, if there is an obstacle in this region, a position of a joint portion of a combined birds-eye-view image is varied (for example, refer to Patent Reference 2).